Purpose:Photon counting detectors with its energy resolving ability is a rapidly evolving technology that allows providing spectral information.One potential application of photon-counting detectors is material identification and quantification by using dual-energy techniques.Therefore,the three-compartment characterization of materials can be challenging with dual-energy techniques.The objective of the this study was to demonstrate feasibility of using gold nanoparticles as a new contrast agent for spectral-computed tomography(CT) system and decompose the iodine,gold nanoparticles and lipid materials to visualizing human carotid arteries in the spectral-CT system.